I am getting invisalign soon and fixing my underbite. i am scared that doing this could close my tooth gap which i really want to keep. do you think i could ask the orthodontist to keep the tooth gap while my teeth are being straightened?

Yes, I think you can ask your orthodontist. They will advise you if that can be accomplished.

You can always ask. We cannot diagnose or provide a second opinion without the benefit of an examination and appropriate diagnostic material. Assuming you are seeing a specialist Orthodontist, trust his/her extensive training and experience to help guide you to the most healthful decision.